Polymer semiconductors—materials that have been made soft and stretchy but
still able to conduct electricity—hold promise for future electronics that
can be integrated within the body, including disease detectors and health
monitors.
Yet until now, scientists and engineers have been unable to give these
polymers certain advanced features, like the ability to sense biochemicals,
without disrupting their functionality altogether.
Researchers at the Pritzker School of Molecular Engineering (PME) have
developed a new strategy to overcome that limitation. Called
"click-to-polymer" or CLIP, this approach uses a chemical reaction to attach
new functional units onto polymer semiconductors.
Using the new technique, researchers developed a polymer glucose monitoring
device, demonstrating the possible applications of CLIP in human-integrated
electronics. The results were published August 4 in the journal Matter.
"Semiconducting polymers are one of the most promising materials systems for
wearable and implantable electronics," said Asst. Prof. Sihong Wang, who led
the research. "But we still need to add more functionality to be able to
collect signals and administer therapies. Our method can work broadly to
incorporate different types of functional groups, which we hope will lead to
far-reaching leaps in the field."
Functionalizing polymers without decreasing their efficacy
To achieve new functionalities of these semiconducting polymers—also
referred to as conjugated polymers—many researchers have previously tried to
build them from scratch by incorporating advanced features into the
molecular designs directly. But conventional procedures for doing this have
failed, either because the molecules have been unable to withstand the
conditions needed to attach them to the polymer chains, or because the
synthesis process decreased their efficacy.
To overcome this, Wang, with graduate student Nan Li, developed the CLIP
method, which uses a copper-catalyzed azide-alkyne cycloaddition to add
functional units to a polymer. Because this "click reaction" happens after
the polymer is created, it does not affect its initial properties much.
Not only that, the reaction could be used in bulk functionalization of the
polymer and in surface functionalization—both essential for creating
functional electronics.
A potentially game-changing system
To demonstrate the effectiveness of CLIP, the researchers attached units
that could photo-pattern the polymer, important for designing circuits
within the material. They also added functionality to directly sense
biomolecules. Their biomolecule sensor used a glucose oxidase enzyme to
detect glucose, which then causes changes to the polymer's electrical
conductance and amplifies the signal.
Now the group is building upon their success by adding other bio-active and
biocompatible functionalities to these polymers, which Li says "has the
potential of becoming a game-changing technology."
"We hope researchers across the field will use our method to endow even more
functionality into this material system and use them to develop the next
generation of human-integrated electronics as a key tool in healthcare,"
Wang said.
Reference:
A universal and facile approach for building multifunctional conjugated
polymers for human-integrated electronics, Matter (2021).
DOI: 10.1016/j.matt.2021.07.013